Fuel supply means for power plants



April 2l, 1942. J. H. wlLsoN 2,280,140

FUEL SUPPLY MEANS FOR POWER PLANTS Filed` Nov` 28,' 1939 /7//6 5f/f3 "gPatented Apr. 2li, 1942 `UNITED STATES PATENT OFFICE 2,280,140 rum.svrrmr MEANS Foa rowaa rmwrs John Hart Wilson, Wichita Falls, Tex.

Application November 28, 1939, Serial No..306,58l

4 Claims.

Ther` present invention relates to fuel supply systems for power plantsand particularly to fuel lines for conveying fuel from the fuel storagetank of an airplane to a carbureting device.

It is, of course, well-known that the lines or conduits for supplyingfuel and lubricating oils to the engines of aircraft are subjectedtointense `vibration when theaircraft is in motion. Be-

cause of such vibration the fuel and oil lines have developed leaks dueto cracking. or have become entirely broken on numerous occasions, thuspermitting fuel such as gasoline or lubricating oil to escape,immediately creating a most dangerous fire hazard. Various attempts havebeen made to safeguard fuel and oil supply conduits and to reduce thedangers of leakage but, despite such prior suggestions, and actualattempts to solve the problems involved, disasters because of fires areof not infrequent occurrence. It is the purpose of the present inventionto provide a novel and improved fuel supply means which not only tendsto minimize the possibility of breakage ofy a fuel supply line but alsoeliminates the possibility of dangerous leakage even when breakageoccurs.

The fuel line which comprises the subject matter of the presentinvention includes three concentrically disposed tubular members, theinner and outer tubes being of ductile metal and the intermediate tubebeing of spongy or resilient material, rubber or a synthetic rubber-likematerial I being preferred. The three tubular members are coextensive inlength and the two metallic tubes closelyengage the inner and outersurfaces of, the intermediate resilient tube which intermediate tubeacts as a cushion, absorbing and damping the vibrations of the innermosttube and thus prolonging its useful life.

The intermediate tube of resilient material is longitudinally grooved orotherwise apertured to receive and maintain a body of gas underpressure. Means is provided for maintaining in the space thus set asidea body of non-combustible gas under a pressure which is higher than thepressure obtaining within the innermost tube, that is, the gaseous bodybetween the inner and outermost tubes is under a pressure superior tothat of the pressure of the gasoline or other fuel Withim the innertube. Hence, should a crack or break` occur in the inner tube, and suchcrack or break be continuedthrough the intermediate tube to a recesscontaining non-combustible gas under pressure, the gas will then passinwardly into the inner tube and the liquid fuel will not pass outwardlyinto the gas recess. When this occurs the operator will soon realizethat the fuel line is broken, as the non-combustible gas will be passingto the carbureting device of the engine, and will take appropriatesteps. It is preferred, however, to provide auxiliary means forindicating at once that the fuel line has been broken or cracked or,alternatively, to provide a valve in association with the fuel linewhich will close the inner tube or conduit immediately upon breaking orcracking thereof. 1

p The invention is susceptible of being embodied in numerous forms inadapting the same to fuel supply systems which vary in constructionaldetails and for the purpose of disclosure one embodiment is illustratedin the accompanying drawing.

In the drawing: Figure l1 is a diagrammatic view of `an entire fuelsupply means in which the invention is incorporated: Y

Figure 2 is a view of portion of the mechanism shown in Figure 1 upon alarger scale and partially broken away, the automatic valve interposedin the fuel line being' shown in section;

`views illustrating the method of providing the end sealing connectionsof the Jacketed conduit.

In Figure 1 of the drawing a gasoline supply tank is diagrammaticallyindicated at Il, a carbureti-ng device at Il, a fuel pump at l2, a flaskor receptacle for a gas under pressure at I3 and a portion of aninstrument panel at Il, an indicating device Il being shown to bemounted upon the panel Il. The distance between the fuel tank It and thecarbureting device may vary greatly, being relatively short in someinstances and relatively long in others. In the fuel supply meansillustrated three sections of the novel and improved fuel line are madeuse of, these sections being indicatedat a. b and c. Each sectionincludes an inner tubular member II of ductile metal, an outer tubularmember il of preferably the same material` such as copper, and anintermediate tubular member Il of resilient rubberlike material, eithernatural or synthetic rubber or rubber-like substance, preferably asubstance which resists attack of hydrocarbon products such as gasolinesand lubricating oils while at the same time is sufiiciently resilient tocomprise a cushioning means for cushioning or damping out vibrations ofthe inner tube I6 relatively to the outer tube I1.

This fuel line comprises a single integral bendable tubular member forthe purpose of assembly in an airplane or motor vehicle and may be bentaround curves without injury. In fabricating the fuel line the resilientcushion-like member I6 is first assembled upon the outer surface of theinner tube I9 and this may be done, and preferably is done, by anextrusion process so that the inner surface of the intermediate tubularmember Il intimately engages the outer surface of the inner tube I6.Formed exteriorly in the intermediate tubular member I6 are a series oflongitudinal grooves I9 which comprise recesses for the reception andmaintenance of bodies of gas under pressure, in the operation of thefuel supply system. The grooves I9 may well be formed in the tubularmember at the time of extrusion. Following the formation of the innerand intermediate tubes the outer tube l1 is applied and this is firstapplied loosely, i. e., with a clearance between the outer surface ofthe intermediate member I3 and the inner surface of the outer tube I1.After having been placed over the intermediate tube the outer tube iscontracted so that its inner surface very closely engages the outersurface of the intermediate tube. This contraction may conveniently beeffected by a drawing operation, the three concentrically arranged tubesbeing drawn through a die such as indicated at 20 in Figure 5. Thisdrawing operation contracts the outer tube diametrically, the outer tubebeing ductile, and brings the outer and intermediate tubes into thedesired stated relationship. The fuel or oil line thus formed is thenready for use and may be severed into lengths for the purpose ofconnecting the various essential elements of the fuel supply system.

The portion a of the fuel line, shown in Figure l, extends from the fueltank to a point adjacent a valve housing 22. The portion b extends fromthe valve housing 22 to the pump I2 and portion c from the pump I2 tothe carburetor II. The ends of the recesses I9 of each of these sectionsare closed by suitable closure means, as by fittings 23, so that gasintroduced into the various recesses cannot escape at the ends of thesections a, b, and c. In Figures 6 and 7 the details of the fittings 23are more clearly illustrated. In making these connections, the innertube I6 is severed at the proper point, as shown in Figures 6, the outertube I1 is cut at a point considerably short of the point of severanceof the inner tube, and by means of a special tool the groovedrubber-like intermediate member I8 is reamed out for a further distanceinwardly of the end of the outer tube I1. The outer tubing clamp nut 45is placed around the end of the jacketed conduit and, by means ofcertain known instrumentalities, the outer tube I1 is flared as at 46 toflt the inner contour of the nut. Then the inner tubing clamp nut 49 isthreaded within the outer nut 45, and, when tightened, securely clampsthe flared end of tube I1. The projecting end of the inner tube I6 isthen flared outwardly as at 49 against the inclined surface of the nut48; and finally, the connecting or coupling fitting .'ili4 is threadedwithin the nut 43 and serves to securely clamp the end of the tube I6.The other end of this connecting fitting I0 is threaded into one of theT-couplings 6I as shown in Figure 2 of the drawing. Gas. such as carbondioxide under pressure, f'lows from the flask I3 through conduit 24,when the valve 24' is opened, to a sleeve-like fitting 26 encircling thefuel line b, the interior of the fitting 26 being in communication,through suitable apertures formed in the outer tube I1 of line b, withall of the grooves I9. The pressure in these grooves will be maintainedabove that in the fuel line by admitting gas to the proper degree ofpressure through the valve 24'.

Fitting 29 is connected by a duct 26 with a fitting 21 encircling thefuel line section a so that the grooves I9 of section a are likewiseillled with gas under pressure.

By means of a by-pass 26, connecting fitting 29 encircling conduit b andfitting 30, encircling conduit c, the gas under pressure existing withinthe channels I9 of conduit b is communicated to the correspondingchannels of conduit c, around the fuel pump I2. It will thus be seenthat, by the provision of the gas conduits mentioned, the

recesses I9 oi' all three sections a, b, and c of` the fuel line aresupplied with gas under pressure from a single source and, by the properactuation of valve 24 or by making use of any suitable gas pressureregulating means (not illustrated) the pressure within the fuel supplymain may be maintained at any predetermined value. This pressure mayvary considerably but in every instance should be greater than thepressure of the liquid fuel within the fuel supply line.

It will be appreciated that, should the inner tube IB become broken dueto crystallization or excessive vibration, or even cracked, andcommunication is established by a further rupture of the intermediatetubular member I6 between one or more of the gas channels I9 and theinterior of tube I6, the gas will force its way into the tube I6 andwill not permit the flow of fuel outwardly. The presence of gas in thefuel line will naturally interfere with the operation of the pump I2 andcarbureting device I I and hence interfere with the operation of theengine being supplied with fuel. This in itself will indicate to theoperator that the fuel line is broken and will cause him to takeappropriate steps. Nevertheless it is desirable to provide means whichmore immediately indicates to the operator that such breakage hasoccurred and, if desired, to provide automatic means for instantlyinterrupting the flow of fuel upon breakage or cracking of the innertube I6.

In Figure l an indicator I5 is shown to be mounted upon the instrumentpanel I4 and connected to the by-pass duct 26 by means of a conduit 33.Also connected to by-pass duct 26, by conduit 34, is a chamber 36 abovea diaphragm 36 of flexible nature the edges of which are clamped betweenthe upper and lower parts of the diaphragm chamber generally indicatedThe valve housing 22 has a downwardly facing annular valve seat 38against which the vertically movable valve 39 may seat. The stem 40 ofvalve 39 is connected to the diaphragm 36. A spring 4I normally urgesthe valve toward closed position but the valve is normally maintained inits open position by gas pressure in the chamber 36 above diaphragm 36,this pressure being sufficiently great to deflect diaphragm 36downwardly against the resistance of springv 4I. 'Ihe valve 39 remainsopen so long as the gas pressurein the system remains at or above apredetermined amount, but if either the outer I or the inner metallictube I6 or I1 should rupture or break, the gas will leak out of thejacket and, the valve 2,4' being closed, the reduced pressure in thesystem will permit the spring 4I vto close the valve 39. The indicatorI5 will then immediately respond to the reduction in pressure and informthe pilot of the break in the fuel line. The operator may, however, inthe case of necessity, open the manually operable valve 42 controllingflow of fuel through bypass 43, thus re-establishing the flow of motivefuel to the carbureting device despite the leakage which has alreadybeen indicated by the mechanism described. The operator, however, hasbeen fully informed of the break in the fuel line and will of coursetake such steps as he can, immediately, to prevent the occurrence of Aafire and to guide his craft as quickly as possible to a point whereadequate repairs may be made.

Various changes and modifications may be made in the embodimentillustrated and described herein without departing from the scope of theinvention as dened by the following claims.

Having thus described the invention, what is claimed as new andv desiredto beV secured by Letters Patent is:

1. In a fuel supply means for power plants, in combination, a fuel tank,a carbureting device, and a fuel line leading from said tank to saiddevice, said fuel line comprising` a fuel conducting tube, means formaintaining around said tube a gas under pressure greater than thepressure of the liquid within the tube, and means also subjected to thepressure of said gas for automatically closing said tube `when the gaspressure in said means falls.

2. In a fuel supply means for power plants, in combination, a fuel tank,a carbureting` device, and a fuel line leading from said tank to saiddevice, said fuel line comprising a liquid fuel conducting tube, a valvefor closing said tube, a chamber for a gas under pressure without thetube, and means for eifecting closure of said valve when the pressure ofthe gas in said chamber falls below a predetermined amount.

3. The combination set forth in claim 2 in which a by-pass is providedfor conducting liquid fuel around the said valve when closed, flowthrough said by-pass being controlled by'a manually operable valve.

4. In a fuel supply means for power plants, in combination, a fuel tank,a carbureting device, and a fuel line leading from said tank to saiddevice, said fuel line comprising a liquid fuel conducting tube, a valvefor closing said tube, a chamber for a gas under pressure enveloping thetube, and a movably mounted element subjected at all times to thepressure of -the gas in said chamber, said valve being op-

